maven报错 java.lang.NoClassDefFoundError: org/codehaus/plexus/compiler/util/scan/InclusionScanException
问题的解决方案会在文章的中间给出，请一步一步阅读。
Maven是一个非常强大的构建工具，能够帮助我们自动化构建过程，从清理、编译、测试到生成报告，再到打包和部署，Maven都可以。
Maven对于项目目录结构、测试用例命名方法等内容有既定的规则，只要遵循这些规则，用户在项目间切换的时候就免去了额外学习的成本，也就是约定优于配置（Convention Over Configuration）。
第一个Maven项目
创建
采用IDEA
File -> New -> Project
选择Maven（不要勾选Create from archetype）
填写Maven的三坐标（GroupId，ArtifactId、Version）
SNAPSHOT是快照的意思，说明该项目处于开发中，是不稳定的版本，随着项目的发展，Version会不断更新，如升级为1.0，1.1-SNAPSHOT，1.1，2.0等。
填写Project name和项目保存的路径
完成之后生成的项目骨架
Maven的约定
pom.xml在项目的根目录下
假设该目录为${proj-dir}，那么Maven有以下假设：
${proj-dir}/src/main/java —— 存放项目的.java文件。${proj-dir}/src/main/resources —— 存放项目资源文件，如spring, hibernate，log4j等配置文件。${proj-dir}/src/test/jave —— 存放所有测试.java文件，如JUnit测试类。以*Test.java命名${proj-dir}/src/test/resources —— 测试资源文件。${proj-dir}/target —— 项目输出位置。项目的路径
编写简单的helloworld
该Hello类所在的报名要与GroupId、ArtifactId相吻合。
引入Junit依赖，在pom.xml中
编写测试用例
采用Maven来构建项目
用Maven来运行测试用例
运行会报错
C:\Java\jdk1.7.0_21\bin\java -Dmaven.multiModuleProjectDirectory=C:\Users\GWCheng\IdeaProjects\maven-hello -Dmaven.home=D:\servers\apache-maven-3.3.9 -Dclassworlds.conf=D:\servers\apache-maven-3.3.9\bin\m2.conf -Didea.launcher.port=7532 "-Didea.launcher.bin.path=C:\Program Files (x86)\JetBrains\IntelliJ IDEA 15.0.4\bin" -Dfile.encoding=UTF-8 -classpath "D:\servers\apache-maven-3.3.9\boot\plexus-classworlds-2.5.2.jar;C:\Program Files (x86)\JetBrains\IntelliJ IDEA 15.0.4\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMain org.codehaus.classworlds.Launcher -Didea.version=15.0.4 -s E:\JavaLibrary\.m2\settings.xml test[INFO] Scanning for projects...[INFO] [INFO] ------------------------------------------------------------------------[INFO] Building maven-hello 1.0-SNAPSHOT[INFO] ------------------------------------------------------------------------[WARNING] The POM for org.apache.maven.plugins:maven-compiler-plugin:jar:3.1 is missing, no dependency information available[INFO] [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-hello ---[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent![INFO] Copying 0 resource[INFO] [INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ maven-hello ---[WARNING] The POM for org.apache.maven.plugins:maven-compiler-plugin:jar:3.1 is missing, no dependency information available[WARNING] Error injecting: org.apache.maven.plugin.compiler.CompilerMojojava.lang.NoClassDefFoundError: org/codehaus/plexus/compiler/util/scan/InclusionScanException at java.lang.Class.getDeclaredConstructors0(Native Method) at java.lang.Class.privateGetDeclaredConstructors(Class.java:2413) at java.lang.Class.getDeclaredConstructors(Class.java:1855) at com.google.inject.spi.InjectionPoint.forConstructorOf(InjectionPoint.java:245) at com.google.inject.internal.ConstructorBindingImpl.create(ConstructorBindingImpl.java:99) at com.google.inject.internal.InjectorImpl.createUninitializedBinding(InjectorImpl.java:658) at com.google.inject.internal.InjectorImpl.createJustInTimeBinding(InjectorImpl.java:882) at com.google.inject.internal.InjectorImpl.createJustInTimeBindingRecursive(InjectorImpl.java:805) at com.google.inject.internal.InjectorImpl.getJustInTimeBinding(InjectorImpl.java:282) at com.google.inject.internal.InjectorImpl.getBindingOrThrow(InjectorImpl.java:214) at com.google.inject.internal.InjectorImpl.getProviderOrThrow(InjectorImpl.java:1006) at com.google.inject.internal.InjectorImpl.getProvider(InjectorImpl.java:1038) at com.google.inject.internal.InjectorImpl.getProvider(InjectorImpl.java:1001) at com.google.inject.internal.InjectorImpl.getInstance(InjectorImpl.java:1051) at org.eclipse.sisu.space.AbstractDeferredClass.get(AbstractDeferredClass.java:48) at com.google.inject.internal.ProviderInternalFactory.provision(ProviderInternalFactory.java:81) at com.google.inject.internal.InternalFactoryToInitializableAdapter.provision(InternalFactoryToInitializableAdapter.java:53) at com.google.inject.internal.ProviderInternalFactory$1.call(ProviderInternalFactory.java:65) at com.google.inject.internal.ProvisionListenerStackCallback$Provision.provision(ProvisionListenerStackCallback.java:115) at org.eclipse.sisu.bean.BeanScheduler$Activator.onProvision(BeanScheduler.java:176) at com.google.inject.internal.ProvisionListenerStackCallback$Provision.provision(ProvisionListenerStackCallback.java:126) at com.google.inject.internal.ProvisionListenerStackCallback.provision(ProvisionListenerStackCallback.java:68) at com.google.inject.internal.ProviderInternalFactory.circularGet(ProviderInternalFactory.java:63) at com.google.inject.internal.InternalFactoryToInitializableAdapter.get(InternalFactoryToInitializableAdapter.java:45) at com.google.inject.internal.InjectorImpl$2$1.call(InjectorImpl.java:1016) at com.google.inject.internal.InjectorImpl.callInContext(InjectorImpl.java:1092) at com.google.inject.internal.InjectorImpl$2.get(InjectorImpl.java:1012) at org.eclipse.sisu.inject.Guice4$1.get(Guice4.java:162) at org.eclipse.sisu.inject.LazyBeanEntry.getValue(LazyBeanEntry.java:81) at org.eclipse.sisu.plexus.LazyPlexusBean.getValue(LazyPlexusBean.java:51) at org.codehaus.plexus.DefaultPlexusContainer.lookup(DefaultPlexusContainer.java:263) at org.codehaus.plexus.DefaultPlexusContainer.lookup(DefaultPlexusContainer.java:255) at org.apache.maven.plugin.internal.DefaultMavenPluginManager.getConfiguredMojo(DefaultMavenPluginManager.java:517) at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:121) at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207) at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153) at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80) at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51) at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128) at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307) at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193) at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106) at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863) at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288) at org.apache.maven.cli.MavenCli.main(MavenCli.java:199) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289) at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229) at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415) at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356) at org.codehaus.classworlds.Launcher.main(Launcher.java:47) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)Caused by: java.lang.ClassNotFoundException: org.codehaus.plexus.compiler.util.scan.InclusionScanException at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50) at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:271) at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:247) at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:239) ... 61 more[INFO] ------------------------------------------------------------------------[INFO] BUILD FAILURE[INFO] ------------------------------------------------------------------------[INFO] Total time: 22.637 s[INFO] Finished at: 2016-03-24T13:34:34+08:00[INFO] Final Memory: 6M/90M[INFO] ------------------------------------------------------------------------[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project maven-hello: Execution default-compile of goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile failed: A required class was missing while executing org.apache.maven.plugins:maven-compiler-plugin:3.1:compile: org/codehaus/plexus/compiler/util/scan/InclusionScanException[ERROR] -----------------------------------------------------[ERROR] realm = plugin>org.apache.maven.plugins:maven-compiler-plugin:3.1[ERROR] strategy = org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy[ERROR] urls[0] = file:/E:/JavaLibrary/.m2/repository/org/apache/maven/plugins/maven-compiler-plugin/3.1/maven-compiler-plugin-3.1.jar[ERROR] urls[1] = file:/E:/JavaLibrary/.m2/repository/org/codehaus/plexus/plexus-utils/1.1/plexus-utils-1.1.jar[ERROR] Number of foreign imports: 1[ERROR] import: Entry[import from realm ClassRealm[maven.api, parent: null]][ERROR] [ERROR] -----------------------------------------------------: org.codehaus.plexus.compiler.util.scan.InclusionScanException[ERROR] -> [Help 1][ERROR] [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.[ERROR] Re-run Maven using the -X switch to enable full debug logging.[ERROR] [ERROR] For more information about the errors and possible solutions, please read the following articles:[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginContainerExceptionProcess finished with exit code 1定位到错误发生的地方
[WARNING] Error injecting: org.apache.maven.plugin.compiler.CompilerMojojava.lang.NoClassDefFoundError: org/codehaus/plexus/compiler/util/scan/InclusionScanException意思是说注入org.apache.maven.plugin.compiler.CompilerMojo的时候找不到org/codehaus/plexus/compiler/util/scan/InclusionScanException
我找了半天在InfoQ上找到了合理的解释
Maven官方有两个插件列表，第一个列表的GroupId为org.apache.maven.plugins，这里的插件最为成熟，具体地址为：http://maven.apache.org/plugins/index.html。第二个列表的GroupId为org.codehaus.mojo，这里的插件没有那么核心，但也有不少十分有用，其地址为：http://mojo.codehaus.org/plugins.html。
InfoQ的连接
http://www.infoq.com/cn/news/2011/05/xxb-maven-8-plugin/
从InfoQ的解释和报错信息来看，是我们的maven在编译时采用的插件没找到
去maven官网的编译插件瞅瞅
http://maven.apache.org/plugins/maven-compiler-plugin/
发现了一个重要信息
在Usage中我们去访问plugin’s wiki page 我们发现
这就是错误的根本原因，原来codehaus不可用了
顺着它给的思路去配置maven，这个感兴趣的读者可以试一下，我试了，不起作用，还有一点我用eclipse是可以执行了，可能eclipse默认采用org.apache.maven.plugins插件，而IDEA采用org.codehaus.mojo吧，我也想不明白？既然是maven的配置文件配置的，IDE工具只是负责加载，为什么会不一样呢？
不想那么多了，还是看看怎么解决吧
进入usage页面
http://maven.apache.org/plugins/maven-compiler-plugin/usage.html
发现了解决方案
<build> <pluginManagement> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.5.1</version> <configuration> <!-- put your configurations here --> </configuration> </plugin> </plugins> </pluginManagement> </build>按照各个配置一下pom.xml
我的配置如下，将下面的代码放在dependencies之后
<build> <pluginManagement> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.5.1</version> <configuration> <!-- put your configurations here --> <source>1.7</source> <target>1.7</target> </configuration> </plugin> </plugins> </pluginManagement> </build>设置maven编译器级别有一篇博客写的很清楚
http://blog.csdn.net/xyls12345/article/details/24990665
我们再次运行上面的test命令
结果如下
C:\Java\jdk1.7.0_21\bin\java -Dmaven.multiModuleProjectDirectory=C:\Users\GWCheng\IdeaProjects\maven-hello -Dmaven.home=D:\servers\apache-maven-3.3.9 -Dclassworlds.conf=D:\servers\apache-maven-3.3.9\bin\m2.conf -Didea.launcher.port=7534 "-Didea.launcher.bin.path=C:\Program Files (x86)\JetBrains\IntelliJ IDEA 15.0.4\bin" -Dfile.encoding=UTF-8 -classpath "D:\servers\apache-maven-3.3.9\boot\plexus-classworlds-2.5.2.jar;C:\Program Files (x86)\JetBrains\IntelliJ IDEA 15.0.4\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMain org.codehaus.classworlds.Launcher -Didea.version=15.0.4 -s E:\JavaLibrary\.m2\settings.xml test[INFO] Scanning for projects...[INFO] [INFO] ------------------------------------------------------------------------[INFO] Building maven-hello 1.0-SNAPSHOT[INFO] ------------------------------------------------------------------------[INFO] [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-hello ---[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent![INFO] Copying 0 resource[INFO] [INFO] --- maven-compiler-plugin:3.5.1:compile (default-compile) @ maven-hello ---[INFO] Changes detected - recompiling the module![WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent![INFO] Compiling 1 source file to C:\Users\GWCheng\IdeaProjects\maven-hello\target\classes[INFO] [INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ maven-hello ---[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent![INFO] skip non existing resourceDirectory C:\Users\GWCheng\IdeaProjects\maven-hello\src\test\resources[INFO] [INFO] --- maven-compiler-plugin:3.5.1:testCompile (default-testCompile) @ maven-hello ---[INFO] Changes detected - recompiling the module![WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent![INFO] Compiling 1 source file to C:\Users\GWCheng\IdeaProjects\maven-hello\target\test-classes[INFO] [INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ maven-hello ---[INFO] Surefire report directory: C:\Users\GWCheng\IdeaProjects\maven-hello\target\surefire-reports------------------------------------------------------- T E S T S-------------------------------------------------------Running com.gwc.mavenlearn.hello.HelloTestTests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.063 secResults :Tests run: 1, Failures: 0, Errors: 0, Skipped: 0[INFO] ------------------------------------------------------------------------[INFO] BUILD SUCCESS[INFO] ------------------------------------------------------------------------[INFO] Total time: 36.692 s[INFO] Finished at: 2016-03-24T15:28:58+08:00[INFO] Final Memory: 14M/114M[INFO] ------------------------------------------------------------------------Process finished with exit code 0从输出可以看出命令执行完成，测试用例也顺利运行了，而且项目中还多了一个target文件夹
这就是maven为我们做的，它会用我们刚才配置的那个插件编译我们的代码
[INFO] Compiling 1 source file to C:\Users\GWCheng\IdeaProjects\maven-hello\target\test-classes然后帮我们执行了测试用例
[INFO] [INFO] --- maven-compiler-plugin:3.5.1:testCompile (default-testCompile) @ maven-hello ---这就是Maven的强大之处，只要我们遵循Maven的约定，它就能自动地执行清理、编译、测试到生成报告，再到打包和部署。
我们package
Maven会帮我们把项目打包
命名规则是ArtifactId-Version.jar命名的。
参考文献
许晓斌. Maven实战[M]. 机械工业出版社, 2011.
InfoQ的文章
Maven官网
一篇博客